A = imread('lena.tif');
F = fft2(double(A),512,512);
F1 = mat2gray(fftshift(log10(1+abs(F))));
%figure,imshow(F1);
%figure,imshow(A);
for a = 0 : 0.2 : 1
    T = dFRT(512,a);
    F2 = T*double(A)*T;
    s = sprintf('a = %.1f',a);
    if(a <= 0.5)
        F3 = mat2gray(log10(1+abs(F2)));
    else
        F3 = mat2gray(fftshift(log10(1+abs(F2))));
    end
    figure,imshow(F3),title(s);
end